diff options
Diffstat (limited to 'Documentation/block')
| -rw-r--r-- | Documentation/block/biodoc.txt | 2 | ||||
| -rw-r--r-- | Documentation/block/biovecs.txt | 10 | ||||
| -rw-r--r-- | Documentation/block/queue-sysfs.txt | 10 |
3 files changed, 19 insertions, 3 deletions
diff --git a/Documentation/block/biodoc.txt b/Documentation/block/biodoc.txt index fd12c0d83..5be8a7f4c 100644 --- a/Documentation/block/biodoc.txt +++ b/Documentation/block/biodoc.txt @@ -1109,7 +1109,7 @@ it will loop and handle as many sectors (on a bio-segment granularity) as specified. Now bh->b_end_io is replaced by bio->bi_end_io, but most of the time the -right thing to use is bio_endio(bio, uptodate) instead. +right thing to use is bio_endio(bio) instead. If the driver is dropping the io_request_lock from its request_fn strategy, then it just needs to replace that with q->queue_lock instead. diff --git a/Documentation/block/biovecs.txt b/Documentation/block/biovecs.txt index 74a32ad52..25689584e 100644 --- a/Documentation/block/biovecs.txt +++ b/Documentation/block/biovecs.txt @@ -24,7 +24,7 @@ particular, presenting the illusion of partially completed biovecs so that normal code doesn't have to deal with bi_bvec_done. * Driver code should no longer refer to biovecs directly; we now have - bio_iovec() and bio_iovec_iter() macros that return literal struct biovecs, + bio_iovec() and bio_iter_iovec() macros that return literal struct biovecs, constructed from the raw biovecs but taking into account bi_bvec_done and bi_size. @@ -109,3 +109,11 @@ Other implications: over all the biovecs in the new bio - which is silly as it's not needed. So, don't use bi_vcnt anymore. + + * The current interface allows the block layer to split bios as needed, so we + could eliminate a lot of complexity particularly in stacked drivers. Code + that creates bios can then create whatever size bios are convenient, and + more importantly stacked drivers don't have to deal with both their own bio + size limitations and the limitations of the underlying devices. Thus + there's no need to define ->merge_bvec_fn() callbacks for individual block + drivers. diff --git a/Documentation/block/queue-sysfs.txt b/Documentation/block/queue-sysfs.txt index 3a29f8914..e5d914845 100644 --- a/Documentation/block/queue-sysfs.txt +++ b/Documentation/block/queue-sysfs.txt @@ -20,7 +20,7 @@ This shows the size of internal allocation of the device in bytes, if reported by the device. A value of '0' means device does not support the discard functionality. -discard_max_bytes (RO) +discard_max_hw_bytes (RO) ---------------------- Devices that support discard functionality may have internal limits on the number of bytes that can be trimmed or unmapped in a single operation. @@ -29,6 +29,14 @@ number of bytes that can be discarded in a single operation. Discard requests issued to the device must not exceed this limit. A discard_max_bytes value of 0 means that the device does not support discard functionality. +discard_max_bytes (RW) +---------------------- +While discard_max_hw_bytes is the hardware limit for the device, this +setting is the software limit. Some devices exhibit large latencies when +large discards are issued, setting this value lower will make Linux issue +smaller discards and potentially help reduce latencies induced by large +discard operations. + discard_zeroes_data (RO) ------------------------ When read, this file will show if the discarded block are zeroed by the |